There are many types of thermotherapeutic pads available. Many use envelopes that are filled with a heat transfer material. The pad can then be heated or cooled to provide the desired thermotherapeutic effect.
Thermotherapeutic pads that use plastic envelopes can suffer from several problems. When the pad is cooled, the envelope may become stiff and unable to easily conform to the body part needing thermal therapy. In addition, condensation may occur at the surface of the envelope, which can cause discomfort. When the pad is heated, the envelope may become excessively hot, which can be potentially unsafe to the user. Although wrapping the pad in a towel has been suggested by some as a possible solution, a person who follows this advice may unknowingly and detrimentally reduce the thermotherapeutic effect by selecting an improper thickness of towel or a towel made of an unsuitable material.
In addition, the heat or cold bearing material inside known thermotherapeutic pads often has a tendency to collect, under influence of gravity or other forces, at locations away from the body part in need of thermal therapy.
Hence, existing thermotherapeutic pads, and particularly those with plastic envelopes, suffer from a number of problems.